This is the 2398th most frequent Turkish word.
güneyindeki
"South of" or "to the south of."
In this sentence, 'güneyindeki' is used to specify a location relative to the south of a larger entity, Turkey. It modifies 'şehirlerden', indicating cities located in the south part of Turkey.
İstanbul, Türkiye'nin güneyindeki şehirlerden birisi değildir.
Istanbul is not one of the cities in the south of Turkey.
Here, 'güneyindeki' describes a positional relationship, showing that the garden is in a section that is south of the house. It modifies 'bir bölümde', pointing out the area or section.
Bahçe, evin güneyindeki bir bölümde yer alıyor.
The garden is located in a section south of the house.
In this usage, 'güneyindeki' is describing the location of the hills relative to the south of a town. It establishes a spatial relationship of the hills to the town.